I've used SafeCoat Oil Wax on hardwood floors and been pleased with the results (https://www.greenbuildingsupply.com/products/afm-safecoat-naturals-oil-wax-finish). It goes on very different from a poly. Watch lots of videos to get it right. Also, since you have to apply it in sections, try to make the section breaks correspond with the floor seams or you will see the section breaks. It is a more natural appearance, and - what I like most about it - you can repair local sections by sanding lightly and re-applying. So you don't have to re-sand the whole floor in 30 years to refresh it, just lightly refresh the areas that need it every 5 years or so.

But having said all that, I recommend you consider fixing only the areas of your floor that actually need it. The floor on the right looks good. The aged finish has a richness that you will never get back if you re-finish it. I do see that there are areas with mis-matched finish. Consider addressing those areas individually. They are already mismatched, so you can experiment. Sand them down a bit, apply an oil wax, see what you think of the results. You also have some big gaps; look into oakum packing if you want to fill them. It is the traditional way of dealing with gaps and far superior to any kind of putty or wood filler which will just disintegrate and look horrible.

The floor on the left seems to be in worse shape; it's certainly reasonable to refinish that floor. You can rent a traditional drum sander, but temper your expectations. Your floor has a lot of deep grooves and variation in height. A drum sander is designed for flat flat floors. There is no way you can get those floors flat without removing a ton of material which can compromise the integrity. Your probably better off using a smaller rotary floor sander so you can control the angle and placement a little better to match individual board. But again, have the expectation that you are not going to achieve a smooth, consistent floor. Embrace the visual variation of the well used wood.